There are a variety of diseases which can debilitate humans and animals, including bacterial infections, viral infections, fungal infections and parasites. Science and medicine are continually searching for better and more effective methods and compositions for curing or alleviating these diseases and their associated effects. Many times, the diseases can develop in concert with each other, one pathogen attacking one part of the subject while a separate pathogen attacks another. Unfortunately, many treatments are very disease or pathogen dependent and not all treatments are effective.
Antibiotics have been in use for almost a century to fight bacterial infections. Over time, antibiotics are losing the fight against bacteria. Production of new antibiotics has not kept up with the ability of bacteria to adapt and become resistant. Alternatives to antibiotics are desirable and necessary to fight harmful pathogens. Bacteria strains that are resistant to antibiotics are on the increase. Research continues in an effort to keep up with and discover new and effective therapeutic compositions and methods which can be used in the treatment of a variety of diseases and disorders.
Silver is known to be antimicrobial. It is effective and non-toxic when used in small quantities. Silver has been shown to have antibacterial, antiviral and antifungal properties. It is believed that the silver ions disrupt the respiratory functions or other functions of single-celled bacterial microorganisms, and may also disrupt membrane functionality or link to the cell's DNA. Silver is known to have antimicrobial effects on over 650 disease-causing germs. The present invention is harmless to the body when used in the low quantities needed for the antimicrobial action to occur, especially since the formulation provides an efficiently controlled, gradual release of free silver ions.
A major drawback when using silver as against pathogens, however, is that the larger particle silver cannot necessarily all be processed and expelled by the body, and excess silver can collect in the pigment of the skin. This excess silver causes a cosmetic condition called argyria, where the skin has a bluish tinge.
Recent technology developments now make it possible to manufacture nanoparticles of silver, as well as silver ions, in solution. Although bacteria can be controlled with larger particle silver, larger particle silver does not seem to be effective against viruses. Silver nanoparticles of ten (10) nanometers and smaller have been shown to exhibit similar antimicrobial properties as silver ions, particularly with respect to viruses. For viruses, it is believed that the silver nanoparticles (and/or the silver ions) disrupt the ability of the virus to bind to cell receptor sites.
Particle surface area contact affects the efficacy of the silver against pathogens. The greater the silver particle surface area in contact with a pathogen, the better the antimicrobial properties seem to be. As silver particle size decreases, the surface area of a quantity of silver particles increases. A quantity of smaller particle silver of, for example, the nanometer size, has much more surface area than larger particles of silver of the same quantity. As a result, the same amount of large particle silver has much less effectiveness against pathogens as a much smaller amount of nanoparticles; that is, to obtain the same surface area as larger particles of silver, much less nanoparticle silver is necessary. Smaller quantities of nanoparticle silver can be used to obtain the same desired surface area so that the total amount of silver used is well below the threshold of that which would cause argyria.
During recent years, materials containing silver have shown a substantial increase in popularity. Those containing silver ions and silver nanoparticles are increasingly regarded as a reasonably safe and effective antimicrobial agent.
Delivering bioavailable silver ions for utilization on the body is a challenge because silver ions are electrically attracted to a host of substances on the body. Silver ions in contact with the body will rapidly form complexes or compounds with other materials in the air and on or in the body, and these complexes or compounds will not have the antimicrobial properties of the silver ions, resulting in the silver ion becoming unavailable to perform the appropriate topical
Silver ions are on the increase use in medical applications, particularly as a natural alternative to traditional antibiotics. Ionic silver is being used in topical dressings to treat wounds and to prevent and treat infections and contamination from harmful pathogens. However, these topical dressings have their drawbacks and shortcomings.
If silver ions are used topically and they are not shielded (or part of a bioactive particle, complex or compound), there is only a brief opportunity for them to perform the antimicrobial function—where and when they make contact with the body. Because of their high reactivity, the ions are reacted almost immediately with any topical application. Thus, topical formulations containing silver ions may be initially highly antimicrobial, but as the silver ions quickly react, the topical formulation loses its antimicrobial properties and becomes ineffective.
Various silver-containing chemical substances have been also been tried and used in the past in an effort to gain a sustaining antimicrobial benefit, but these substances too have generally proven to be minimally effective in or on the body because they also immediately deliver all of their silver content as free silver ions—silver ions that combine with other substances to lose their antimicrobial properties. Examples include U.S. Pat. No. 3,761,590 (complexes the silver ion to the antibiotic sulfadiazine to form silver sulfadiazine, a form of silver salt); U.S. Pat. No. 4,906,466 (complexes silver ions to titanium oxide; U.S. Pat. Nos. 5,429,819 and 6,093,414 (utilizes silver thiosulfate ion complexes). As well, some of these substances, such as silver nitrate, are undesirably toxic to the human body when administered in typical doses.
To avoid the immediate exhaustion of the topically applied silver ions, it is desirable to develop a way of delivering silver ions over time.